Emergency shutdown system

ABSTRACT

Fires in kitchen appliances are detected and controlled by a detection and control system that activates a fire extinguishing system when the fire is detected, terminates the supply of electricity and/or gas to the appliances, and initiates audible and visual alarms. The audible alarm can be terminated, while the visual alarm continues until the system is restored to a pre-detection state. The system includes a control circuit, and a fire detection means with a moveable member that engages a normally closed microswitch in the control circuit to open the control circuit. Relays in the control circuit change state upon opening of the control circuit to de-energize the appliance, and audible and visual alarms are activated. The audible alarm can be manually terminated. However, the visual alarm remains activated until the system is recharged and returned to the ready state.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates generally to a system for automaticallyshutting down cooking appliances and/or associated equipment inaccordance with NFDA recommended standards in the event of a fire, andin particular to a fail-safe system of this type that will also shutdown in the event of a failure in the system, and which will continue toindicate a failure until corrections are made by authorized personnel.

(2) Description of the Prior Art

Commercial kitchens and related facilities having a plurality of cookingappliances are normally equipped with a fire extinguishing mechanismthat is automatically activated in the event of a fire, such as a greasefire, at one of the appliances. The extinguishing mechanism is usuallycomprised of a source of an extinguishing chemical that is connected viaa piping network to discharge ports that are directed toward the cookingsurfaces of the appliance. A discharge valve is used to control the flowof chemicals from the source. The discharge valve is adapted to beopened when an associated mechanism detects a fire.

For example, a spring-loaded discharge valve may be held in a closedposition by a taut cable, which includes one or more fusable heat linkspositioned above the cooking appliances. When one of the links is meltedby the heat from a cooking fire, the cable is released, opening thedischarge valve, and discharging fire extinguishing chemicals onto thesurfaces of the cooking appliances to extinguish the fire.

An effective, complaint fire extinguishing system must also includemeans to disconnect the cooking appliances from the energy source when afire is detected. Otherwise, the fire-extinguishing chemical will beexhausted, and the fire may continue or restart due to the continuingsupply of energy, i.e., electricity or gas. In the case of an electricalappliance, the appliance is de-energized by opening the electricalcircuit to the appliance. In the case of an gas fueled appliance, theappliance is de-energized by shutting off the gas supply, e.g., byclosing a valve, such as a solenoid actuated valve.

An effective system should also include an alarm to alert others to theexistence of the fire. This alarm can be activated at the time thechemical is discharged, and continues to emit a signal, e.g., a soundand/or a light signal, until manually disconnected. The inclusion of asignal mechanism is mandated by NFPA-17A of the National Fire ProtectionCodes for “Wet Chemical Extinguishing Systems” used for restaurantcanopy hoods. NFPA-17A states:

“A signal shall be provided to show that the system has operated, thatpersonnel response is needed, and that the system is in need ofrecharge. The extinguishing system shall be connected to the fire alarmsystem, if provided, in accordance with the requirements of NFPA 72,National Fire Alarm Codes, so that the actuation of the extinguishingsystem will sound the fire alarm as well as provide the function of theextinguishing system.”

Various fire extinguishing systems for use with restaurant cookingappliances have been proposed in the prior art. The following patentsare representative of prior art systems:

3,653,443 Dockery 4,356,870 Gaylord et al. 4,675,541 Peters et al.4,773,485 Silverman 4,830,116 Walden et.al. 4,979,572 Mikulec 5,127,479Stehling et al. 5,297,636 North 5,351,760 Tabor. Jr. 5,628,368 Sundholm5,871,057 Stehling et al.

Despite considerable efforts, there is still a need for a system foreffectively de-energizing a plurality of cooking appliances and otherrestaurant equipment, as required, in the event of a fire, whileemitting a signal as required by NFPA-17A. In particular, a system ofthis type is needed that will not only de-energize appliances in theevent of a fire, but which will de-energize appliances in the event of adetected failure in the microswitch or other circuit component.Therefore, the user will not be falsely assured that a functional systemis being used to monitor conditions when, in fact, the system is notfunctioning.

A system of this type should also be designed so that the alarm cannotbe fully deactivated until the system has been recharged after adischarge of chemical, or has been repaired after a malfunction has beendetected. For example, if the alarm system includes both a sound andlight emitting components, the operator should be prevented fromdisconnected both components until the system has be recharged orrepaired by authorized and skilled personnel.

SUMMARY OF THE INVENTION

The present invention is directed to a shutdown or control system forde-energizing kitchen appliances in the event of a fire. The system isused in conjunction with a fire extinguishing system comprised of asource of fire extinguishing chemical or other material, a releasemechanism for releasing the fire extinguishing material in the event ofa fire.

Basically, the shutdown system is comprised of a normally closed switch,positioned to be opened when the fire extinguishing system is activated,a plurality of relays that change state when the switch is opened, therelays being capable of de-energizing appliances, and an alarm mechanismthat includes an audible component that can be deactivated by anoperator, and a visual component that can only be deactivated by repairand recharging of the fire extinguishing system.

Preferably, the normally closed switch is positioned in the path of acomponent of the fire extinguishing system that moves from a readyposition to a released position when a fire is detected, so that thecomponent engages the switch to move the switch from a closed state toan open state. For example, the switch can be a microswitch that ispositioned adjacent a component of a fire extinguisher discharge valvecontrol mechanism that moves from a restrained position to a releasedposition when a fire is detected, so that the component engages themicroswitch when at the released position.

More specifically, the fire extinguishing system may be comprised of acontrol mechanism that includes a pivotal member moveable between firstand second positions, with the pivotal member being urged toward thesecond position by a spring, and held in the first position by a cablethat includes a heat fusable link. In the event of a fire, the heatfusable link is severed by the heat from the fire, releasing the cableand allowing the pivotal member to move under the influence of thespring to the second position.

A microswitch is positioned at the second position in the path of thepivotal member, so that a component of the pivotal member engages themicroswitch to move the switch from the closed state to the open state.The pivotal member also engages a release member, such as a valve, torelease fire extinguishing chemicals from a supply source, such as apressurized tank.

The microswitch is in a primary circuit with a plurality of relays thatare in secondary circuits with different appliance controllers, e.g.,switches or valves. The circuits are designed so that the circuits tothe appliances are in a closed or completed state when the microswitchis closed. These circuits may be designed with the relays in an openstate or a closed state. Thus, for purposes of description, when theappliances are energized, the relays will be described as being in theenergized state, and in the deenergized state when the appliances aredeenergized.

The microswitch is also in a circuit with an audible alarm, such as ahorn, and a visual alarm, such as a strobe light. The audible and visualalarms are in a deenergized state when the microswitch is closed, andare moved to the energized state when the microswitch is opened. Thehorn is also in a circuit with a switch that can be used to deactivatethe horn.

During the monitoring cycle, the control system is plugged into a powersource, normally a 120 volt AC source, that provides energy to a closedprimary circuit including the microswitch and a plurality of appliancecontrol relays that are each connectable to a switch or valve(collectively referred to as controllers) that is interposed between anappliance or other powered device in the kitchen area, and itsrespective source of energy. The primary circuit is also connected tosecondary circuits that include audible and visual alarms.

Fires are detected by a fire detection system that includes a tensionedcable positioned above the areas where fires may occur. For example, thecable may be positioned inside a hood that is located over the cookingapplicances. The cable includes heat fusable links above each appliance.Such links are known in the relevant art and include means forconnecting cable segments to opposite sides of the link, with the linkbeing constructed of a material that melts at relatively lowtemperatures.

When exposed to a cooking fire, the link melts to separate the cable.The cable is attached to a moveable member, preferably a pivotal memberthat has a pivot end and a distal end. The pivotal member is held at arestrained position when the cable is under tension, and moves to areleased position when the cable is released.

The fire extinguishing system also includes a source of fireextinguishing chemicals, e.g., a pressurized tank, and conduits or apiping network leading from the fire extinguishing chemical source todischarge nozzles positioned above the cooking appliances. A normallyclosed control valve is positioned between the chemical source and thenozzles, preventing discharge of chemicals. This valve is positioned inthe path of, and engaged by, the moveable member when the movable memberis in the released position.

The microswitch in the control circuit is also positioned in the path ofthe moveable member, and is also engaged by the moveable member in thereleased position. Thus, when the moveable member is released, themoveable member contacts the fire extinguisher valve, opening the valveto release the extinguishing material. Also, the moveable membercontacts the microswitch to open the primary control circuit. As aresult, the relays in the primary circuit change state, activating thecontroller, e.g., opening an electrical switch, or closing a controlvalve. As a result the supply of energy, e.g., electricity or gas, isterminated.

Another relay in the primary circuit is also in a second circuit with anormally open, audible alarm circuit, and a normally open visual alarmcircuit. Opening of the primary circuit causes the relay to changestate, closing the alarm circuits to activate the audible and visualalarms, thereby alerting appropriate personnel. The audible alarm can beimmediately deactivated by a pushbutton switch or another kind of aswitch. However, no provision for opening the visual alarm circuit isprovided. Therefore, the visual alarm continues to signal until theprimary circuit is restored to its closed state. This restoration cannotoccur until the microswitch is again closed, which requires authorizedpersonnel to recharge the fire extinguishing system and restore thecable to its tensioned state.

Accordingly, one aspect of the present invention is to provide anemergency shutdown system to deenergize appliances upon activation of afire extinguishing system comprising a microswitch moveable between froma closed position to an open position upon activation of the fireextinguishing system. A plurality of relays are in a first circuit withthe microswitch, each of the relays being in a second circuit with anapplicance controller. The second circuits are closed when themicroswitch is in a closed position, and the relays change from a firststate to a second state, opening the second circuits when themicroswitch is moved to an open position. An audible alarm is in thecircuit with the microswitch, the audible alarm being moveable from anunenergized state to an energized state when the microswitch is opened,the audible alarm also being in a circuit with a silencing switchadapted to return the audible alarm to the unenergized state. A visualalarm is also in the circuit with the microswitch, the visual alarmbeing moveable from an unenergized state to an energized state when themicroswitch is opened, the visual alarm being returnable to theunenergized state only when the fire extinguishing system is returned tothe recharged and ready state.

Another aspect of the present invention is to provide a fire controlsystem for use with at least one kitchen appliance comprising a firedetection means to activate a fire extinguishing system; a fireextinguishing system activated upon detection of a fire; and a controlsystem. The control system includes a microswitch moveable between froma closed position to an open position upon detection of a fire; aplurality of relays in a first circuit with the microswitch, each ofsaid relays being in a second circuit with an applicance controller; thesecond circuits being closed when the microswitch is in a closedposition. The relays change from a first state to a second state andopen the second circuits when the microswitch is moved to an openposition. An audible alarm is in a circuit with the microswitch, withthe audible alarm being moveable from an unenergized state to anenergized state when the microswitch is opened, the audible alarm alsobeing in a circuit with a silencing switch adapted to return the audiblealarm to the unenergized state. A visual alarm is also in the circuitwith the microswitch, the visual alarm being moveable from anunenergized state to an energized state when the microswitch is opened,the visual alarm being returnable to the unenergized state only whensaid fire extinguishing system is returned to the recharged and readystate.

These and other aspects of the present invention will become apparent tothose skilled in the art after a reading of the following description ofthe preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a fire detection and extinguishing systemjoined to the control system.

FIGS. 2 and 3 are diagram of the electrical circuit of the preferredembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, terms such as horizontal, upright,vertical, above, below, beneath, and the like, are used solely for thepurpose of clarity in illustrating the invention, and should not betaken as words of limitation. The drawings are for the purpose ofillustrating the invention and are not intended to be to scale.

FIG. 1 illustrates a fire detection system, generally 10, that includesa tensioned cable 12 positioned above a typical cooking appliance 14.Cable 12 includes a plurality of heat fusable links 16 positioned aboveburners 18. Cable 12 has a fixed end 20 attached to a support, and isstrung around pulleys 22 to attach at its opposite end to a pivotalmember 24. Member 24 includes a pivotal end 26, a first contact element28 and a second contact element 30. Spring 32 urges pivotal member 24 ina downward direction toward a released position. Pivotal member 24 isheld in a restrained position, as illustrated, by cable 12.

A fire extinguishing system comprises a pressurized container 34connected by conduit 36 through normally closed control valve 38 todischarge nozzles 39 positioned above burners 18. Valve 38 is mountedfor engagement by contact element 30 of pivotal member 24 when member 24is in the released position. Microswitch 40 is positioned for engagementby contact element 28 of pivotal member 24 when member 24 is in thereleased position.

Refer now to FIG. 2 and FIG. 3. The control system, generally 50, iscomprised of a lockable housing 52, with a strobe light 54 and audiblealarm release button 56 on the front panel of housing 52. A circuitboard 58, audible alarm 60, and relevant wiring (not shown) are mountedinside housing 52.

As best illustrated in FIG. 2, the circuit of the invention is comprisedof first and second DPDT relays R1 and R2 that are in a primary circuitwith DPDT relay R3, and SPST relays R4 and R5. Relay R1 is connected toterminal blocks TB4 and TB5, and relay R2 is connected to terminalblocks TB6 and TB7. Pin connector J1 connects the primary circuit tostrobe 54 and horn 60. TB 2 connects to a 120 volt AC source rated at amaximum of 10 amps.

The 120 volt AC input power is connected to terminal block TB2,terminals 3, 4, and 5. These connections are referred to herein by theabbreviations TB2-3, TB2-4, and TB2-5. Other connections will besimilarly abbreviated. TB2-3 is used for connection of the hot, 120 voltpower source side. TB2-4 is used for connection of the neutral side ofthe 120 volt power source. TB2-5 is used for connection of the 120 voltAC input ground wire. Terminal block TB3 connects the primary circuit tomicroswitch 40.

TB2-3 grounding wire is routed, via a solder joint connection, to thechassis connection between circuit board 58 and housing 52 to allowfurther connection to earth ground via conduit connections per theNational Electric Code requirements. TB2-3 is routed to J1-8 (pushbuttoncommon) and TB3-6 (remote microswitch common). TB3-6 is connected toR3-6 and R3-5.

The 120 volt AC neutral connection, TB2-4, is routed to TB1-1 (remotecontactor), which is connected to J1-3 (power light), J1-7 (horn), andJ1-8 (strobe light). TB1-1 is also attached to R1-7 (coil), R4-8 (coil),and to R2-8, R3-7 and R5-7. The 120 volt AC ground connection, TB2-5, isrouted to the chassis ground connection located on circuit board 58.

During normal operation, AC current is routed TB3-6 to the commonconnection of microswitch 40. The normally closed contact of microswitch40 is then routed back to TB3-7, and from TB3-7 to R1-8 (coil) and R3-8(coil) of R2 and R5. Since a circuit now complete, relays R1, R2, R3,and R5 are energized. The relay contacts of R1 and R2 are routed toterminal blocks located on circuit board 58. R1 contacts are routed toTB4-8 (common), TB4-9 (normally open), TB4-10 (normally closed), TB5-11(normally closed), TB5-12 (normally open), and TB5-13 (common). R2contacts are routed to TB6-14 (common), TB6-15 (normally open), TB6-16(normally closed), TB7-17 (normally closed), TB7-18 (normally open), andTB7-19 (common).

TB-4, TB-5, TB-6, and TB-7 are adapted to connect with connectors(either electrical switches or valves) used to control the flow ofenergy (either electricity or gas) to appliances. Relay contacts arerated 10 amps at 24 volts DC, 120 and 220 volts AC. Relay R3, whenenergized (the “normal” condition), transfers 120 volt AC hot, from pinR3-4 (normally open when relay R3 is not energized) to TB1-2. TB-1 willthen create a 120 volt AC output for remote connection of relays orcontactors rated for “normally energized” use. The 120 volt AC output israted at 10 amps at 24 volts DC, 120 and 220 volts AC.

Using normal operating conditions, the contacts of microswitch 40 are inthe normally closed position, all relay contacts are in the workingposition, and the remote contactor/relay output is energized. Upon lossof wiring integrity between TB3-6 and TB3-7, due to opening ofmicroswitch 40 or a fault in the field wiring, 120 volt AC power will belost to Relays R1, R2, R3, and R5, causing contacts on TB-4, TB-5, TB-6,and TB-7 to change state. Output on TB1-1 and TB1-2 will drop out.

The 120 volt AC hot, connected to R3-6 (common) will now be routed frompin 2 (normally open when R3 is energized under normal operatingcondition) to J1-2. J1-2 is routed to the + input of strobe light 54.120 volt AC hot, connected to R3-5 (common) is routed from pin 1(normally open when R3 is energized under normal operating condition),to R4-6 (common). R4-6 (common) is routed through R4-2 (normallyclosed), which is then routed to J1-3, which is connected to an the +input of horn 60. The circuit is now in “alarm” condition, shutdownrelay contacts have operated, the contactor/relay output is deactivated,alarm horn 60 is sounding, and strobe light 54 is flashing.

Depressing momentary pushbutton 56 causes contact closure of a normallyopen contact block. One side of the contact block is connected to J1-1,and the other side of the contact block is connected to J1-4. Closure ofthe contact block allows 120 volt AC power to pass from J1-1 (120 voltAC hot), to J1-4, which is connected to R5-6 (common). R5-6 (common) isrouted to R5-2 (normally open when R5 is energized under normaloperating condition). R5-2 is connected to R4-3 (normally open when R4is energized under normal operating condition), and R4-7 (coil).

R4 is thereby energized, allowing power from R4-6 (via contact pin 3) tothe coil. This is in turn energizes the relay in a “latched” mode. WithR4 in a “latched” mode (energized), R4-2 (normally open under normaloperating condition) returns to a normally open state, and breaks the120 volt AC Hot connection directed to J1-3, in turn silencing alarmhorn 60. Even though horn 60 has been silenced, strobe light 54 willstill flash, the shutdown contacts will remain in the “off” mode, andthe contactor/relay output remain de-energized. Strobe 54 continues toflash until the fire detection system has be repaired, the fireextinguishing systems have been recharged, and the entire system hasbeen returned to its ready state.

Certain modifications and improvements will occur to those skilled inthe art upon a reading of the foregoing description. It should beunderstood that all such modifications and improvements have beendeleted herein for the sake of conciseness and readability but areproperly within the scope of the follow claims.

What is claimed is:
 1. An emergency shutdown system to deenergizeappliances upon detection of a fire by a fire detection systemcomprising: a) a microswitch moveable between from a closed position toan open position upon activation of said fire extinguishing system; b) aplurality of relays in a first circuit with said microswitch, each ofsaid relays being in a second circuit with an appliance controller; saidsecond circuits being closed when said microswitch is in a closedposition, said relays changing from a first state to a second state andopening said second circuits when said microswitch is moved to an openposition; c) an audible alarm in a circuit with said microswitch, saidaudible alarm being moveable from an unenergized state to an energizedstate when said microswitch is opened, said audible alarm also being ina circuit with a silencing switch adapted to return said audible alarmto the unenergized state; and d) a visual alarm in circuit with saidmicroswitch, said visual alarm being moveable from an unenergized stateto an energized state when said microswitch is opened, said visual alarmbeing returnable to the unenergized state only when said fireextinguishing system is returned to the ready state.
 2. The system ofclaim 1, wherein said microswitch is moved from said closed state tosaid open state by a component of said fire detection system.
 3. Thesystem of claim 1, wherein said appliance controller is an electricalswitch in a circuit with an electrical appliance.
 4. The system of claim1, wherein said appliance controller is a valve in a fuel line connectedto a gas appliance.
 5. The system of claim 1, further including alockable housing, with said visual alarm being positioned on theexterior of said housing.
 6. The system of claim 1, wherein said firstcircuit is a 120 volt AC powered circuit.
 7. A fire control system foruse with at least one kitchen appliance comprising: a) a fire detectionsystem to detect a fire; b) a fire extinguishing system activated upondetection of a fire by said fire detection system; c) a microswitchmoveable between from a closed position to an open position upondetection of a fire; d) a plurality of relays in a first circuit withsaid microswitch, each of said relays being in a second circuit with anappliance; said second circuits being closed when said microswitch is ina closed position, said relays changing from a first state to a secondstate and opening said second circuits when said microswitch is moved toan open position; e) an audible alarm in a circuit with saidmicroswitch, said audible alarm being moveable from an unenergized stateto an energized state when said microswitch is opened, said audiblealarm also being in a circuit with a silencing switch adapted to returnsaid audible alarm to the unenergized state; and f) a visual alarm incircuit with said microswitch, said visual alarm being moveable from anunenergized state to an energized state when said microswitch is opened,said visual alarm being returnable to the unenergized state only whensaid fire extinguishing system is returned to the ready state.
 8. Thesystem of claim 7, wherein said fire detection means includes atensioned cable having heat fusable links positioned above saidappliance.
 9. The system of claim 8, wherein said fire detection meansincludes a moveable member moveable from a first position to a secondposition upon detection of a fire, said fire extinguishing systemincluding a valve positioned at said second position for contact withsaid moveable member when said moveable member is at said secondposition, thereby activating said fire extinguishing system.
 10. Thesystem of claim 7, wherein said fire extinguishing system includes asource of fire extinguishing material, at least one discharge nozzleabove said appliance, a conduit leading from said source to said nozzle,and an inline valve in said conduit, said valve being opened upondetection of a fire to permit movement of fire extinguishing materialfrom said source to said nozzle.
 11. The system of claim 7, wherein saidfire detection means includes a moveable member moveable from a firstposition to a second position upon detection of a fire, said microswitchbeing positioned at second position for contact with said moveablemember when said moveable member is at said second position, therebymoving said microswitch for a closed position to an open position.
 12. Afire control system for use with a plurality of kitchen appliancescomprising: a) a cable with heat fusable links positioned above saidappliances, said cable having a fixed end and a second end; b) amoveable member having a restrained position and a released position,said cable second end being attached to said moveable member, said cablebeing under tension when said moveable member is in said restrainedposition; c) a fire extinguishing system activated upon detection of afire; d) a microswitch positioned for engagement by said moveable memberwhen said moveable member is in said released position, said microswitchbeing moved from a normally closed position to an open position whenengaged by said moveable member; e) a plurality of relays in a firstcircuit with said microswitch, each of said relays being in a secondcircuit with an appliance; said second circuits being closed when saidmicroswitch is in said normally closed position, said relays changingfrom a first state to a second state and opening said second circuitswhen said microswitch is moved to an open position; f) an audible alarmin a circuit with said microswitch, said audible alarm being moveablefrom an unenergized state to an energized state when said microswitch isopened, said audible alarm also being in a circuit with a silencingswitch adapted to return said audible alarm to the unenergized state;and g) a visual alarm in circuit with said microswitch, said visualalarm being moveable from an unenergized state to an energized statewhen said microswitch is opened, said visual alarm being returnable tothe unenergized state only when said fire extinguishing system isreturned to the ready state.
 13. The system of claim 12, wherein saidmoveable member is a pivotal member having a pivotal end and a contactelement for contacting said microswitch when in said released position,said pivotal member being attached to said cable second end when in saidrestrained position, and urged toward said released position by aspring, said pivotal member being movable to said released position uponrelease of said cable.
 14. The system of claim 12, wherein said fireextinguishing system includes a source of fire extinguishing material,at least one discharge nozzle directed toward said appliance, a conduitleading from said source to said nozzle, and an inline valve in saidconduit, said valve being engaged by said pivotal member when saidpivotal member is in the released positioned to permit movement of fireextinguishing material from said source to said nozzle.